I had a project I was working on in ArcGIS Pro earlier today in which I had a toolbox with a few models, a script, and FME tools. A few minutes after having closed out Pro, I re-opened it and tried to open the project from the "Recent Projects" link. I then got a "Project not found" error with the message (attachment included), "Sorry, we couldn't find your project. Do you want to remove the project shortcut from your list of recent projects?" Instead of removing it I navigated to the project in Windows Explorer and found the .aprx to be missing along with the toolbox in which I had been doing work. I had searched about this problem a year or two ago (a coworker experienced this problem) and was able to find that a couple people had run into this before, but searching now seems to bring no results. I wanted to ask you all - have you had this problem of ArcGIS Pro disappearing projects before and were you able to recover your projects without restoring previous versions of the project's parent folder? I have spent a long time working on this project and would like to avoid having to start even from a recovery point.
EDIT: Please post here if you have had this problem too! There does not seem to be a solution at this point, but the more people that can share their experiences having this problem the more likely we are to be able to find out where this problem is stemming.